Ethanol-Induced Defects on Zebrafish Retinal Development: Rescue by Nutritional Supplements

poster abstractFetal Alcohol Spectrum Disorder (FASD), a result of prenatal alcohol exposure, produces a wide range of developmental defects including severe ocular defects that include microphthalmia, optic nerve hypoplasia, scotopic vision loss and coloboma. The zebrafish FASD model recapitulates many defects seen in human patients. Ethanol exposure (100 and 150 mM) during early development (midblatula transition through somitogenesis, 2-24 hours post fertilization, hpf) produced severe ocular defects including microphthalmia, optic nerve hypoplasia and photoreceptor differentiation defect. Examining specific terminal differentiation markers showed ethanol-induced defects in differentiation of most retinal cell types. Ethanol exposure altered gene expression of critical transcription factors. Increased cell death accounted for the small eye phenotype, and the retina responds with increased proliferation in the outer nuclear layer, inner nuclear layer, and ciliary marginal zone (CMZ). Ethanol treated retinas showed an expanded CMZ and cell cycle exit defects of the photoreceptor cells. In order to examine progenitor cell populations and differentiation defects in the ethanol treated retinal cells, specific markers for retinal stem, precursor and progenitor cell populations were examined. While control retinas showed terminally differentiated photoreceptors at 72 hpf, ethanol treated retinas expressed immature and nascent photoreceptor markers in cell populations undergoing proliferation. Nutrient co-supplement with retinoic acid (RA) or folic acid (FA) with ethanol during 2-24 hpf rescued photoreceptor differentiation and optic nerve defects. Competitive inhibition of RA synthesis by ethanol was hypothesized by Duester (1991), and rescue of ethanol-induced retinal defects suggest an effect on RA levels in the developing retina. Treatment with RA inhibitors produced retinal defects similar to ethanol-treated embryos. Interestingly, RA supplementation (24-48 hpf and 48-72 hpf) following ethanol treatment (2-24 hpf) restored photoreceptor differentiation suggesting RA provides a critical signal for precursor cell differentiation. In contrast, post-treatment with FA, did not restore retinal cell differentiation. FA functions as a critical component of one-carbon metabolism and can influence histone- and DNA-methyl transferase activities. Molecular mechanisms underlying disruption of cell cycle exit and FA rescue of ethanol-induced defects are being actively studied

Some results on generalized multiplicative perfect numbers

In this article, based on ideas and results by Sándor (J Inequal Pure Appl Math 2:Art. 3, 2001; J Inequal Pure Appl Math 5, 2004), we define k-multiplicatively e-perfect numbers and k-multiplicatively e-superperfect numbers and prove some results on them. We also characterize the k-T0T∗-perfect numbers defined by Das and Saikia (Notes Number Theory Discrete Math 19:37–42, 2013) in details

Non-linear charge reduction effect in strongly-coupled plasmas

The charge reduction effect, produced by the nonlinear Debye screening of high-Z charges occuring in strongly-coupled plasmas, is investigated. An analytic asymptotic expression is obtained for the charge reduction factor which determines the Debye-Hueckel potential generated by a charged test particle. Its relevant parametric dependencies are analyzed and shown to predict a strong charge reduction effect in strongly-coupled plasmas.Comment: 4 figure

Fokker-Planck Kinetic description of small-scale fluid turbulence for classical incompressible fluids

Extending the statistical approach proposed in a parallel paper \cite% {Tessarotto2008-aa}, purpose of this work is to propose a stochastic inverse kinetic theory for small-scale hydrodynamic turbulence based on the introduction of a suitable \textit{local phase-space probability density function} (pdf). In particular, we pose the problem of the construction of Fokker-Planck kinetic models of hydrodynamic turbulence. The approach here adopted is based on the so-called IKT approach (inverse kinetic theory), developed by Ellero et al. (2004-2008) which permits an exact phase-space description of incompressible fluids based on the adoption of a local pdf. We intend to show that for prescribed models of stochasticity the present approach permits to determine uniquely the time evolution of the stochastic fluid fields. The stochastic-averaged local pdf is shown to obey a kinetic equation which, although generally non-Markovian, locally in velocity-space can be approximated by means of a suitable Fokker-planck kinetic equation. As a side result, the same pdf is proven to have generally a non-Gaussian behavior.Comment: Contributed paper at RGD26 (Kyoto, Japan, July 2008